Loads and yields of selected constituents in streams and rivers of Monroe County, New York, 1984-2001

More than 20 years of hydrologic-data collection in Monroe County provides a basis for evaluation of the effects of urban growth and land-use changes on the chemical quality of streams and assessing the effectiveness of current water-resourcemanagement practices. Since 1980, the Monroe County Department of Health has maintained a cooperative agreement with the U.S. Geological Survey (USGS) to collect and analyze hydrologic data from several sites and use the results to identify sources of contamination, quantify the annual loads and yields of selected chemical constituents, and identify temporal trends in these loads. Monroe County encompasses 673 square miles in the Lake Ontario Plain region of New York (fig. 1) (Heffner and Goodman, 1973). Precipitation in this region is evenly distributed throughout the year, averaging about 2.7 inches per month and about 32 inches per year (National Oceanic and Atmospheric Administration, 1983-99) measured at the Rochester-Monroe County Airport (fig. 1). The even distribution of precipitation during the year is a result of the proximity to Lake Ontario and Lake Erie which affect local rain and snowfall patterns. The annual maximum precipitation during 1984-2001 (45.9 inches) occurred during 1998; the minimum (24.8 inches) occurred during 1985 (fig. 2). Loads and Yields of Selected Constituents in Streams and Rivers of Monroe County, New York, 1984-2001